XLR (5-pin) pinout
DMX512 Pinout (5-Pin XLR)
DMX512 uses a 5-pin XLR with pin 1 as signal common, pin 2 as data − , pin 3 as data +, and pins 4/5 reserved for an optional second data link. The standard (ANSI E1.11) specifies 120 Ω shielded twisted-pair cable and a 120 Ω terminator on the last fixture in the line.
| Pin | Signal | Notes |
|---|---|---|
| 1 | Common / shield | Signal common and cable shield. |
| 2 | Data 1 − | Inverted leg of the primary EIA-485 data pair. |
| 3 | Data 1 + | Non-inverted leg of the primary EIA-485 data pair. |
| 4 | Data 2 − (optional) | Second data link, rarely implemented; sometimes used for talkback or RDM alternatives. |
| 5 | Data 2 + (optional) | Second data link, rarely implemented. |
What it’s used for
DMX512 is the standard control protocol for stage lighting: one DMX universe carries 512 channels of 8-bit control at 250 kbit/s over an EIA-485 differential pair. Consoles output DMX; dimmers, moving lights, LED fixtures, and haze machines listen on assigned addresses.
Fixtures daisy-chain: console → fixture → fixture → terminator. The standard allows 32 unit loads per line; opto-splitters extend beyond that and isolate segments against faults.
Wiring & termination notes
- Use 120 Ω DMX/EIA-485 cable, not microphone cable. Mic cable’s lower impedance causes reflections that show up as random flicker and dead fixtures mid-run.
- Terminate the last fixture with a 120 Ω, ≥1/4 W resistor across pins 2 and 3 in a male XLR shell. Many fixtures offer a termination switch instead.
- The 5-to-3-pin adapter wiring is 1→1, 2→2, 3→3. Budget fixtures with 3-pin DMX ports follow the same assignments (pin 2 data −, pin 3 data +).
- Do not tie pin 1 to the connector shell; E1.11 keeps the shield isolated from chassis at the fixture end to avoid ground loops through the data line.
Frequently asked questions
Why does DMX use 5-pin XLR if only 3 pins are used?
The standard reserved pins 4/5 for a second data link and deliberately chose a connector that would not mate with microphone cables, so audio cable would not end up in data lines. Economics undid that on budget fixtures with 3-pin ports.
Can I use a microphone cable for DMX in a pinch?
It can appear to work on short, single-fixture runs, but the impedance mismatch causes reflections, and failures show up as intermittent flicker that is miserable to troubleshoot mid-show. Carry real DMX cable and adapters.
Do I really need a DMX terminator?
Yes on any run of consequence. An unterminated line reflects the signal off the open end; whether it corrupts data depends on cable length and luck. A 120 Ω resistor across pins 2 and 3 at the last fixture removes the variable.